Feeling Fatigued?

When Olympian Blake Russell finds herself feeling progressively fatigued on a training run with each step more labored than the last, she knows what is wrong right away: Her iron levels are low. After ending many seasons through high school and college burned out and exhausted with no apparent cause, she finally discovered that an iron deficiency was the energy-zapping culprit.

Iron deficiency anemia is particularly common among female runners like Russell, but is not unusual in male runners. While running inherently depletes iron, a number of measures can be taken to keep your levels up to par with what the experts recommend. As Russell found out, an awareness of diet and an iron supplement helped her get back on track with building her Olympic resume.

Iron Clad Symptoms

“It wasn’t until after college that I really got a handle on my iron levels,” explains Russell. “Up until then I just knew I would be really wiped out certain times of the year.” Fatigue, it turns out, is one of the main symptoms of iron deficiency anemia.

“If you’re thinking, ‘Normally I’m able to keep this kind of pace or run this distance and feel this way, and now I’m not able to do that,’ then you might have an iron issue,” says Dr. Shawn Dolan, Ph.D., R.D., and a professor of exercise science at California State University at Long Beach. As iron levels drop, perceived exertion soars. “Sometimes we’ll see a decrease in aerobic performance and sometimes a runner is not able to improve during critical times in their training when they should be improving,” says Dolan.

“When my levels are low, I notice that my breathing gets really hard and I labor up the smallest hills,” says Russell. “In general I just feel lethargic and don’t have much energy.”

As Russell found out, low iron equates to low energy. Simply put, “Iron helps your body garner energy from the food that you eat,” explains Dolan. Iron is an important mineral that assists the body with producing hemoglobin, which in turn brings oxygen from the lungs to the body’s tissues — in particular, the working muscles runners depend on.

“If we don’t have adequate iron to create enough hemoglobin, we are doing a disservice to ourselves because the tissues rely on oxygen in order to produce energy,” explains Dolan.

A Running Problem

There is no shortage of academic research that touts the fact that runners are particularly susceptible to iron deficiency anemia. Whether it is iron levels in Division III cross country runners, soldiers during basic combat training, or elite female distance runners, the annals of literature support the link between running and iron deficiencies.

There are several reasons for this relationship. The most obvious way to lose iron is by sweating, and runners do a lot of that, especially when training in hot, humid conditions. Iron can also be depleted through normal GI bleeding that occurs during distance running, as well as through menstruation. Last but not least, pounding on pavement leads to lost iron. Dubbed “footstrike hemolysis,” red blood cells break down with every impact of your foot against the ground, thus contributing to depleted iron levels. This is why runners are more likely to become anemic than, say, swimmers.

Ironing Out the Issue

The higher the volume of training, the more a runner relies on oxygen transport to the muscles. This means that elite runners tend to have greater issues with iron deficiency anemia. Still, Dolan says, “Everyone has an individual response to training.”

Every runner also has his or her own “normal” when it comes to ferritin levels. Ferritin is responsible for the storage and transport of iron in the body, and it's what doctors look for to determine whether a patient might be iron deficient. However, a routine blood test checks hemoglobin and other matters, which can appear fine even if ferritin levels are low — you have to request specifically to have your ferritin checked. “Some people may hover in a lower range, but they perform well and they’re OK that way, whereas other people may not be,” says Dolan. “It’s good to have individual norms as well as general norms.”

That is exactly what Russell discovered. The first few blood tests she took in college suggested she was within normal range; however, when she continued to feel fatigued, it was clear that she required higher-than-average levels. “If I’m feeling really run down and not quite sure what it is, I go get it tested. I now have a baseline number and know where I should be,” she says.

If you suspect that you may be iron deficient, Dolan suggests you have the test run along with other standard blood tests that are taken during a physical exam. If an athlete’s levels are at less than 30–40 micrograms, she generally begins to explore options such as dietary adjustments and iron supplements.

“If the ferritin is significantly low, a supplement will probably be required to bring those levels back up. If it’s on the border, then the runner may be able to improve some of their dietary habits and bring up their levels that way,” says Dolan. Either way, expect it to take a couple of months before levels are completely normalized.

It should be noted that self-diagnosis isn’t the way to go when it comes to iron deficiency anemia. Taking an iron supplement without the guidance of a physician can lead to too much iron in your system. Since iron isn’t a mineral your body simply excretes if it has excess amounts, you could end up with iron toxicity.

In general, Dolan recommends that men over 18 years of age take in 8 milligrams of iron a day and women take in 18 milligrams. After menopause, women can drop down to 8 milligrams. Russell is conscious about taking a supplement, as well as eating red meat a couple times a week, in addition to other iron-rich foods.

On top of the fact that there are few foods that contain high amounts of iron, our bodies only absorb a small percentage of the iron in any food source. As a result, runners have to be strategic in building iron sources into their diets. “Beef is going to give you the most bang for your buck,” says Dolan. Spinach, black and white beans, hummus, chicken, fish and some pastas, breads and cereals that are fortified with iron also provide good sources.

It should be noted that Vitamin C helps to increase your body’s ability to absorb iron. Strawberries on cereal or a spinach salad will boost the amount of iron you absorb from that source. On the flip side, fiber and soy can decrease iron absorption. If a high-fiber cereal is fortified with iron, the amount of iron you actually absorb is less than you may expect.

Dietary changes can be both preemptive and reactive, depending on where your ferritin levels sit. If you find that you have entered into the range of iron deficiency, you may be forced to back off of training slightly; however, Dolan and her colleagues don’t usually tell runners to stop running. As Russell found, once she got a handle on her iron deficiency through diet and supplements several years ago, she has rarely encountered subsequent problems. With a renewed pep in her step, the sub-2:30 marathoner will continue to thrive on the roads and tracks of the elite running scene.

Mackenzie Lobby is a freelance journalist, coach and runner based in Minneapolis, Minn.

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